David W. Harless:
Here is another approach (cut and paste to Command window):
clear
tempfile p1 p2
input beg1 end1 p1
15522 15674 1
15887 16617 1
end
ren beg1 date1
ren end1 date2
g id=1
g i=_n
reshape long date, i(i) j(t1)
la def t 1 "begin" 2 "end"
la val t1 t
format date %d
save `p1'
clear
input beg2 end2 p2
15522 15674 1
15979 16436 1
16557 16587 1
end
ren beg2 date1
ren end2 date2
g id=1
g i=_n
reshape long date, i(i) j(t2)
la def t 1 "begin" 2 "end"
la val t2 t
format date %d
save `p2'
joinby id date using `p1', unm(both) update
drop i _m
sort id date
by id: g inp1=(sum(t1==1)>0)-(t1==2)>0
by id: replace inp1=0 if inp1[_n-1]==0&mi(p1)
by id: g inp2=(sum(t2==1)>0)-(t2==2)>0
by id: replace inp2=0 if inp2[_n-1]==0&mi(p2)
bys id (date): g enddate=date[_n+1]
format enddate %d
order id date enddate t1 t2 p1 p2 inp1 inp2
ren date startdate
drop t1 t2 p1 p2
drop if mi(end)
g david=max(inp1,2*inp2)
li, noo clean
> > David W. Harless
> >
> >
> >
> > I have two data sets containing dates of participation in two related
> > programs, program 1
> > and program 2. But the complication is that the program 1 data set lists
> > dates if the
> > participant is enrolled in *either* program 1 or program 2. Dates in the
> > program 2 data
> > set indicate definite participation in program 2.
> >
> > The best explanation is an example. Here is program participation dates
> > from the program
> > 1 data set. (Date variables have display format %dD_m_Y and I added the
> > program variable
> > to make this explanation clearer):
> >
> > beg1 end1 program
> > 01 Jul 02 30 Nov 02 1
> > 01 Jul 03 30 Jun 05 1
> >
> > And the same individual for the program 2 data set:
> >
> > beg2 end2 program
> > 01 Jul 02 30 Nov 02 2
> > 01 Oct 03 31 Dec 04 2
> > 01 May 05 31 May 05 2
> >
> >
> > I want to combine these records to obtain a data set that looks like:
> >
> > beg end program
> > 01 Jul 02 30 Nov 02 2
> > 01 Dec 02 30 Jun 03 0
> > 01 Jul 03 30 Sep 03 1
> > 01 Oct 03 31 Dec 04 2
> > 01 Jan 05 30 Apr 05 1
> > 01 May 05 31 May 05 2
> > 01 Jun 05 30 Jun 05 1
> >
> > (where the 0 indicates the individual did not participate in either program
> > during that
> > period).
> >
> > There are, of course, many individuals with varying dates of participation
> > in one or both
> > programs. Any suggestions as to how one might solve this problem?
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